枇杷果实锈斑病的发生原因及其控制

以早钟6号、长红3号和解放钟3个枇杷品种为试材,观察果实锈斑发生规律,探讨发病原因,并提出其防治的措施。3个枇杷品种锈斑病的易感性有很大的差异,早钟6号最感病,解放钟次之,长红3号锈斑果发病率最低;果皮蜡质层和细胞壁自发荧光强弱与锈斑病的感病程度有密切的关系,发病率高的早钟6号果皮蜡质层薄,果皮细胞壁自发荧光最弱,而发病率低的长红3号果皮蜡质层最厚,细胞壁自发荧光强且均匀。枇杷果实锈斑的发生主要原因是在不良外界条件下形成微创口,随着果实膨大生长,伤口撕裂,表皮下的局部细胞恢复分生能力,形成木栓形成层,木栓细胞团突破表皮而形成肉眼可见的锈斑;人工抹去表皮毛,可形成微创口,显著加剧锈斑果的发生,而套袋处理可大大降低锈斑发生率,并且越早套袋效果越好。

Causes of occurrence and prevention of russet on loquat fruit

Three loquat cultivars, Zaozhong No.6, Changhong No.3 and Jiefangzhong were used as materials to study the occurrence and possible causes of fruit russeting so as to prevent this physiological disorder.Different loquat cultivars displayed different susceptibility to russeting.Zaozhong No.6 showed the highest incidence of russet,followed in order by Jiefangzhong and Changhong No.3.Russet susceptibility was found to have a close relationship with the structure of the cuticle layer of fruit skin.Under florescent microscope, Changhong No.3 had the thickest cuticle and cell walls with strongest and uniform auto-fluorescence,while Zaozhong No.6 had the thinnest cuticle and the weakest cell wall auto-fluorescence.Russeting might be derived from micro-wounds formed on the skin under some adverse conditions.The micro-wounds lancinated with the expansion of the fruit pulp, and at the same time,some of the cells beneath the epidermis resumed cell division and phellogen developed.The outgrowth of suberized cells broke through the epidermis and formed the visible russet spots.Artificial removal of the skin hairs created such micro-wounds and induced severe russeting in cultivar Jiefangzhong.Fruit bagging significantly reduced russet incidence and the effect was better if bagging was conducted earlier.